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DRIED distillers grains with solubles (DDGS) have become a common ingredient in swine diets because they cost-effectively supply energy, amino acids and phosphorus to the diet.

However, the higher concentration of fiber and unsaturated fatty acids, especially linoleic acid, in DDGS could affect growth and carcass quality when fed at high levels.

There are two feed additives that could diminish some of the negative effects of the fat source and fat characteristics:

1. Conjugated linoleic acid (CLA) — a group of geometric and positional isomers of linoleic acid. Previous studies have shown that the inclusion of CLA in the swine grower/finisher diet could reduce the negative effects of unsaturated fatty acids and improve belly firmness.

2. Ractopamine hydrochloride (Paylean, Elanco) — a phenethanolamine with similar properties to beta-adrenergic agonists that works by directing nutrients from fat deposition toward protein deposition. Previous studies have demonstrated that ractopamine inclusion in swine finishing diets has resulted in improvements in growth performance and carcass quality.

The interactive effects of these two feed additives on growth performance and carcass and fat characteristics when incorporated into swine diets containing DDGS have not been studied.

Swine researchers D. Pompeu, B.R. Wiegand, H.L. Evans, J.W. Rickard, G.D. Gerlemann, R.B. Hinson and G.L. Allee at the University of Missouri-Columbia, S.N. Carr and M.J. Ritter at Elanco Animal Health and R.D. Boyd at The Hanor Co. conducted a study to evaluate the effects of dietary ractopamine, CLA and DDGS on the growth and carcass and fat quality of finishing pigs.

The study used 1,104 barrows and gilts that were allotted to eight treatments, with six replicates, for a total of 23 pigs per pen. Half of the pens had only barrows, and half had only gilts.

All pigs were fed a diet containing 15% DDGS until they reached an average bodyweight of approximately 75 kg. At that time, an acclimation phase was initiated. Half of the pigs were fed a corn/soybean meal diet, and the other half of the pigs were fed a corn/soybean meal diet containing 20% DDGS. These two diets contained 0.75% standard ileal digestible (SID) lysine and 0.46% total phosphorus. Also, 3% choice white grease was added to each diet.

When the pigs reached a bodyweight of approximately 100 kg, they were randomly assigned to the treatment diets (Table 1). Pigs that were fed the corn/soybean diet during the acclimation phase were assigned to the corn/soybean meal treatments, while pigs that were fed the corn/soybean meal diet with 20% DDGS continued with treatment diets that contained 20% DDGS.

Pigs had ad libitum access to feed and water during the 27-day feeding period. Pen feed usage and pen pig weight were recorded every week.

All pigs were harvested on day 27, and various carcass measurements were obtained during harvest and eight hours postmortem. Fat samples were collected from the jowl and belly.

Table 2 summarizes the growth performance and carcass measurements for the eight treatments.

Table 3 summarizes the main effects of diet, ractopamine and CLA on growth performance and carcass measurements.

Table 4 summarizes the effect of treatment and main effects on the fatty acid profile of belly samples.

The researchers provided the following interpretations of the results from this experiment:

* When CLA was included in the diet, average daily feed intake (ADFI) was not affected. However, the addition of CLA resulted in increased overall average daily gain (ADG) and gain:feed, which may have been due to feeding more than 0.5% CLA.

* Feeding DDGS did not significantly affect whole body growth. These findings are in agreement with several previous research projects that included DDGS at levels of up to 40% in grower/finisher diets.

* Supplementing diets with ractopamine increased overall ADG, reduced ADFI and increased gain:feed, which is in agreement with previous studies.

* When CLA was added to either diet, there was a slight improvement in lean dressing percentage.

* Feeding DDGS reduced dressing percentage 0.5% but did not affect any of the carcass characteristics.

* When feeding DDGS, which contains more fiber than corn and soybean meal, there may be an increase in gut fill and intestinal mass, resulting in decreased dressing percentages. Therefore, the researchers suggested measuring growth performance on a carcass basis because carcass weight is the main driver of pig value.

* For all interactions, when ractopamine was added to the corn/soybean meal diets, the difference in fatty acid values was small. However, when ractopamine was added to the DDGS diets, the magnitude of the difference from DDGS diets without ractopamine was increased.

* The addition of CLA to corn/soybean meal diets reduced the ratio of omega-6 to omega-3 fatty acids from 29.6 to 29.0, whereas when CLA was added to the DDGS diets, the ratio was increased from 31.0 to 35.1.

* The iodine value was increased 3.9% in the DDGS diets and 1.9% in the ractopamine diet but decreased 1.7% in the CLA diets compared to the corn/soybean meal diet.

The Bottom Line

This experiment demonstrated that feeding 20% DDGS in grower/finisher diets had no effect on the growth performance or most carcass composition and quality characteristics of the pigs, except for decreased carcass yield and increased iodine value.

CLA diminished some of the negative effects of DDGS, and ractopamine inclusion produced improvements in growth performance and carcass quality.

Reference

J. Anim. Sci. Vol. 91. No. 2.

1. Treatment descriptions

-Diet calculated analysis-

-Diets-

SID lysine

Avail. phos.

Metab. energy

Corn/ soybean

Corn/soy-bean meal

Ractop.

CLA

Treatment

(%)

(%)

(Mcal/kg)

meal

+20% DDGS

(mg/kg)

(%)

1

0.65

0.16

3.44

X

—

0

0

2

0.66

0.16

3.39

X

—

0

0.6

3

0.95

0.20

3.43

X

—

7.4

0

4

0.95

0.20

3.38

X

—

7.4

0.6

5

0.65

0.18

3.41

—

X

0

0

6

0.66

0.19

3.36

—

X

0

0.6

7

0.95

0.20

3.40

—

X

7.4

0

8

0.95

0.20

3.35

—

X

7.4

0.6

2. Growth performance and carcass measurements for eight treatments

-Treatment-

Criteria

1

2

3

4

5

6

7

8

Bodyweight, kg

Day 0

100.3

100.5

100.6

100.4

100.3

100.3

100.3

100.4

Day 27

123.6

124.2

127.9

128.1

122.7

124.3

127.1

128.0

ADG, kg/day

0.86

0.87

1.01

1.03

0.83

0.89

1.00

1.02

ADFI, kg/day

2.81

2.79

2.68

2.67

2.66

2.77

2.59

2.64

Gain:feed

0.308

0.313

0.375

0.385

0.308

0.322

0.385

0.387

Hot carcass weight, kg

91.5

91.3

96.8

95.6

90.5

91.4

94.8

94.7

Carcass dressing, %

73.99

73.55

75.69

74.62

73.72

73.56

74.60

73.94

Carcass gain, kg

0.64

0.64

0.76

0.77

0.61

0.65

0.74

0.75

Carcass gain:feed

0.228

0.230

0.285

0.287

0.229

0.236

0.288

0.285

Back fat depth, mm

21.04

19.98

19.98

19.81

20.74

20.32

19.13

19.18

Loin depth, mm

58.76

60.11

61.60

63.12

58.76

59.06

62.82

62.70

Lean, %

51.93

52.62

52.62

52.92

52.08

52.32

53.15

53.15

3. Main effects of diet, ractopamine and CLA on growth performance and carcass measurements

-Treatments-

Criteria

1-2-3-4

5-6-7-8

1-2-5-6

3-4-7-8

1-3-5-7

2-4-6-8

Bodyweight, kg

Day 0

100.5

100.3

100.4

100.4

100.4

100.4

Day 27

126.0

125.5

123.7

127.8

125.3

126.1

ADG, kg/day

0.94

0.93

0.86

1.01

0.92

0.95

ADFI, kg/day

2.74

2.66

2.76

2.64

2.68

2.72

Gain:feed

0.345

0.350

0.313

0.383

0.344

0.352

Hot carcass weight, kg

93.80

92.85

91.17

95.47

93.39

93.25

Carcass dressing, %

74.46

73.96

73.70

74.71

74.50

73.92

Carcass gain, kg

0.70

0.69

0.63

0.76

0.69

0.70

Carcass gain:feed

0.258

0.259

0.231

0.286

0.257

0.260

Back fat depth, mm

20.20

19.84

20.52

19.53

20.22

19.82

Loin depth, mm

60.90

60.83

59.17

62.56

60.48

61.25

Lean, %

52.52

52.68

52.24

52.96

52.45

52.75

4. Effect of treatment and main effects on fatty acid profile of belly samples